High flex bumper with reinforced corner end sections

Abstract

A bumper beam construction including an elongated tubular beam of high strength but characteristically flexible to absorb substantial energy on impact having a mounting bracket attached at each end of the center section and at least one stiffening bracket attached to each mounting bracket. The mounting brackets extend from the rear wall of the tubular beam and facilitate attachment to a vehicle frame. The stiffening brackets are attached to the mounting brackets and the end sections of the tubular beam outboard of the center section. The stiffening brackets improve the comer impact strength of the tubular beam without adversely affecting the flexibility of the center section. This comer construction arrangement provides for optimal distribution of stress during corner impacts.

The invention claimed is:  
     
       1. A bumper construction for vehicles comprising: 
       an elongated tubular beam having front, rear, top, and bottom walls, and having a center section and end sections, the beam being high strength to absorb substantial energy on impact;  
       a mounting bracket attached at each end of the center section inboard of the end section, the mounting brackets extending from the rear wall and being configured for attachment to a vehicle frame; and  
       at least one stiffening bracket attached to each of the mounting brackets, the at least one stiffening bracket including an arm that extends outboard from the mounting bracket at least about half a length of the end sections and that is attached to an associated one of the end sections, the arms lying closely adjacent one of the top and bottom walls and being securely attached to the one of the top and bottom walls to rigidify the associated one end section for corner impact.  
     
     
       2. The bumper construction defined in claim  1 , wherein the top and bottom walls are relatively planar and generally horizontal when in a car-mounted position, and wherein the arm of the at least one stiffening bracket is attached to one of the top and bottom walls. 
     
     
       3. The bumper construction defined in claim  2 , wherein the at least one stiffening bracket includes a plurality of stiffening brackets where each have an arm welded to one of the top and bottom walls. 
     
     
       4. The bumper construction defined in claim  3 , wherein the at least one stiffening bracket includes a second stiffening bracket attached to the associated one end section, and wherein the first-mentioned stiffening bracket is attached to the top wall and to the mounting bracket, and the second stiffening bracket is attached to the bottom wall and to the mounting bracket. 
     
     
       5. The bumper construction defined in claim  4 , wherein the first-mentioned and second stiffening brackets each include an attachment flange attached to the mounting bracket and further include an intermediate section connecting the attachment flange to the arm. 
     
     
       6. The bumper construction defined in claim  5 , wherein the arm extends to a location between the front and rear walls proximate an end of the end section to which the respective arm is attached. 
     
     
       7. The bumper construction defined in claim  6 , wherein each of the arms is MIG welded at discontinuous locations along edges of the arms. 
     
     
       8. The bumper construction defined in claim  1 , wherein the at least one stiffening bracket includes a plurality of stiffening brackets where each include an attachment flange attached to the associated mounting bracket, an arm attached to one of the top and bottom walls, and further include an intermediate section connecting the attachment flange to the arm. 
     
     
       9. A bumper construction for vehicles comprising: 
       an elongated tubular beam having front, rear, top, and bottom walls that define a cavity, and having a center section and end sections, the beam being high strength to absorb substantial energy on impact;  
       mounting brackets attached at ends of the center section, the mounting brackets extending from the rear wall and being configured for attachment to a vehicle frame; and  
       an energy absorbing system attached to the flexible tubular beam, including a center absorber filling a significant portion of the cavity in the center section to stiffen the center section against buckling collapse, and including end absorbers filling the cavity in a significant portion of the opposing end sections to stiffen the end sections against buckling collapse, an inner surface of the end absorbers being spaced from an associated outer end surface of the center absorber to leave an empty end area in the cavity at the mounting brackets to promote flexibility in an area proximate to the mounting brackets to assist in optimizing energy absorption upon a corner impact on an end of the tubular beam.  
     
     
       10. The bumper construction defined in claim  9 , including a front energy absorber attached to a front wall of the flexible tubular beam. 
     
     
       11. The bumper construction defined in claim  10 , wherein the end absorber includes a first portion that extends into the cavity of the tubular beam and a second portion that engages an outer surface on one of the front, rear, top, and bottom walls. 
     
     
       12. The bumper construction defined in claim  11 , wherein the center absorber comprises a foam insert having a front surface that engages the front wall and a rear surface that engages the rear wall. 
     
     
       13. The bumper construction defined in claim  11 , wherein the front wall includes a non-planar shape, and the front absorber includes a rear surface configured to mateably engage the non-planar shape of the front wall. 
     
     
       14. The bumper construction defined in claim  11 , including top and bottom stiffening brackets at each end of the tubular beam, the top and bottom stiffening brackets each including an arm welded to an associated one of the top wall and bottom wall, and further including a flange attached to an associated one of the mounting brackets. 
     
     
       15. The bumper construction defined in claim  9 , wherein the end absorbers comprise an injection molded piece having walls and recesses therebetween forming a honeycomb-like arrangement optimally suited for strength upon a corner impact directed primarily against one of the end absorbers. 
     
     
       16. The bumper construction defined in claim  15 , wherein the center absorber comprises a foam insert having a front surface that engages the front wall and a rear surface that engages the rear wall. 
     
     
       17. A bumper construction for vehicles comprising: 
       an elongated tubular beam having front, rear, top, and bottom walls, and having a center section and end sections, the beam being high strength to absorb substantial energy on impact, the tubular beam being elongated and defining a longitudinal direction;  
       a mounting bracket attached at each end of the center section, the mounting brackets extending from the rear wall and being configured for attachment to a vehicle frame; and  
       at least one stiffening bracket attached to each of the mounting brackets, the at least one stiffening bracket including an arm that is elongated in the longitudinal direction and that extends outboard from the mounting bracket, the arm lying closely adjacent one of the top and bottom walls and being attached to the one of the top and bottom walls and further being constructed to rigidify the end sections for corner impact.  
     
     
       18. A bumper construction for vehicles comprising: 
       an elongated tubular beam having front, rear, top, and bottom walls, and having a center section and end sections, the beam being high strength;  
       mounting brackets attached at each end of the center section, the mounting brackets extending from the rear wall and being configured for attachment to a vehicle frame; and  
       top and bottom stiffening brackets attached to each of the mounting brackets and to the end sections outboard of the center section, the top stiffening brackets being attached to the top wall and being constructed to rigidify the end sections for corner impact, the bottom stiffening brackets being attached to the bottom wall and being constructed to also rigidify the end sections for corner impact;  
       wherein the top and bottom walls are relatively planar and generally horizontal when in a car-mounted position;  
       wherein the at least one stiffening bracket includes a plurality of stiffening brackets where each have an arm welded to one of the top and bottom walls;  
       wherein the top and bottom stiffening brackets each include an arm, an attachment flange attached to the mounting bracket, and an intermediate section connecting the attachment flange to the arm; the arm extending to a location between the front and rear walls proximate an end of the end section to which the respective arm is attached; each arm being MIG welded at discontinuous locations along edges of the arms; and  
       an energy absorber system attached to the tubular beam, the energy absorber system including a center absorber positioned inside the tubular beam generally in center thereof, an end absorber positioned at least in part inside the tubular beam at an end thereof, and a front absorber attached to a front wall of the tubular beam.  
     
     
       19. A bumper construction for vehicles comprising: 
       an elongated tubular beam having front, rear, top, and bottom walls, and having a center section and end sections, the beam being high strength to absorb substantial energy on impact;  
       a mounting bracket attached at each end of the center section inboard of the associated end section, the mounting brackets extending from the rear wall and being configured for attachment to a vehicle frame; and  
       at least one stiffening bracket attached to each of the mounting brackets, the at least one stiffening bracket including an elongated arm that extends outwardly along the tubular beam and that is attached to the associated end section outboard of the center section, the stiffening brackets being attached to one of the top and bottom walls and being constructed to rigidify the end sections for corner impact; and  
       an energy absorber system attached to the tubular beam, the energy absorber system including a center absorber positioned inside the tubular beam generally in center thereof, an end absorber positioned at least in part inside the tubular beam at an end thereof, and a front absorber attached to a front wall of the tubular beam.